Electrical contact and method of forming the same



March 23, 1967 E JR 3,311,729

ELECTRICAL CONTACT AND METHOD OF FORMING THE SAME Filed Oct. 4, 1965 fnz/en%rjpori erjael J}; ;?g W M,

1 WWWZGM United States Patent 3,311,729 ELECTRICAL CGNTACT AND METHQD 0F FORMING THE SAME Jeremiah Porter Duel], Jr., Libertyville, Ill., assignor to Deringer Mfg. Company, a corporation of Illinois Filed Oct. 4, 1%5, Ser. N 0. 492,636 6 Claims. (Cl. 200166) This invention relates to electrical contacts and more particularly to a new and novel electrical contact and the method of forming the same.

It is the general object of the present invention to produce a new and improved electrical contact together with new methods of forming electrical contacts, particularly those formed of more than one metal.

It is a more specific object of the present invention to provide new methods of forming an electrical contact wherein the contacting surface is formed of a precious metal while the balance of the contact, including the support for the contacting surface, is formed of base metal.

Many precious metals such as silver and platinum posess characteristics which enable them to perform as electrical contacts in a superior fashion. Thus, in many installations where electrical contacts of the finest qualities are desired, such precious metals are often specified to form the contact surface. Because of the fact that the precious or semiprecious metal is required only on exposed contacting face of the electrical contact, ways and means have been sought of forming electrical contacts of two metals, i.e., the precious or semiprecious metal located to form the contact surface and a base metal serving as the support for the contact and the means for securing it in position. Difiiculty has arisen in the past, however, in securing the two metals together to provide a safe and proper contact.

According to the present invention, a dual metal contact comprising a precious or semiprecious metal and a base metal is created by forming the base metal generally into the shape of a rivet having a head and then attaching to the outer free end of the stem a terminal portion of the precious metal. When the rivet-like body is inserted in an opening and the free end deformed into a head-like body, the outer surface of the deformed portion is made up of the precious or semiprecious metal, thus accomplishing the desired result in a manner which is readily adaptable to mass production of contacts, particularly in automatic or semiautomatic machines.

Other and further objects of the present invention will become readily apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of an electrical contact arm carrying an electrical contact made in accordance with the present invention;

FIG. 2 is an elevational view showing a rivet-like body formed in accordance with the present invention;

FIG. 3 is a vertical sectional view showing a rivet-like body in place in an opening in a contact arm prior to the deformation thereof;

FIG. 4 is a view like FIG. 3 subsequent to the deformation of the rivet-like body; and

FIG. 5 is a view like FIG. 3 of a somewhat modified form of the invention.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail several embodiments of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

Referring now to the drawings, there is shown in FIG.

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2 a generally rivet-shaped body having a stem portion 10 and a head portion 11. The stem 10 is formed of a first part 12 adjacent the head, which may be of copper or other base metal, with the outer free end of the stem being formed of silver as indicated at 13. The head 14 of the rivet is of the same metal as the stem portion 12, in this case copper, and may, where a double contact is desired, he provided with an outer layer of silver as indi-' cated at 15. It will be noted that the cover 15 is provided with a downwardly extending rim portion 16 overlapping the outer layer of the head 14. When the rivet-like body is inserted in an opening 17 provided in a contact arm 18 and then deformed, a double-faced contact such as shown in FIGS. 1 and 4 is formed. It will be noted that the contact therein provided has a first silver contact face 15, and on the opposite side of the arm 18 a second silver contact face designated 20, which is made up of course of the silver which previously formed the free end portion 13. The two silver contacts are spaced apart and supported by the head and stem portions 12 and 14 as shown.

Where but a single silver contact is desired, the structure shown in FIG. 5 may be used, wherein there is provided a rivet-like body 21 having a head 22 and a first stem portion 23 of copper or other similar metal, with the outer free end portion 24 of the stem being formed of a precious or semiprecious metal such as silver. When the rivet is inserted through a suitable opening 25 in a contact arm 26 and then deformed, a silver contact similar to the contact 20 is created with the contact being supported by the head and stem portions 22 and 23 similar to the supports provided for the contact 20.

It will be noted, particularly in the embodiment of FIG. 5, that the precious or semiprecious metal forms only the outer end of the stem and does not cover any other portion of the rivet-like body. Similarly with the first embodiment of the invention, the outer end 13 has the identical construction as the end 24, while the second silver contact 15 covers only the head portion 14 of the rivet, leaving the portions of the rivet body between the head 15 and end portion 13 formed completely of the second or base metal, namely, copper.

In the preferred form of construction, the contact portion 15 is brazed to the head portion 14 and the stem portions 12 and 13 are similarly connected together by brazing and form the rivet-like body which is later to be deformed into the contact illustrated.

It will be clear to those skilled in the art that a relatively large saving in precious metal is effected by the use of a contact forming body of the type described above, and those portions of the final contact which are not exposed and hence are not required to be of the finer metal are formed completely of a baser metal such as copper or the like. While a savings in cost is achieved, the rivetlike body is still in a form which may readily be transformed into an electrical contact by existing machines, preserving all of the advantages of the all silver rivetlike bodies which are in present, relatively wide, use.

I claim:

1. The method of forming a silver contact carried by a baser metal which comprises forming the baser metal into the shape of a rivet having a head and a stem and providing a silver end portion on the free end of said stem, inserting the stem into an opening having a diameter less than the diameter of said head, and then deforming said rivet to flatten the silver end portion into a head-like contact.

2. The method of claim 1 including the steps of providing said head of baser metal with an outer surface of silver to constitute a second silver contact connected to the first contact by said baser metal.

3. The method of forming a contact of one metal car- Patented Mar. 28, 1967 ried by a dilferent metal which comprises forming said different metal into the shape of a rivet having a head and a stem and providing the free end of said stem with an end portion of said one metal, inserting the stem into an opening having a diameter less than the diameter of said head, and then deforming said rivet to flatten said end portion into a head-like contact.

4. As a new article of manufacture, a metal body in the shape of a rivet having a head formed at least in part by a first metal, a stem of a second metal joined to said head with the free end of said stern formed of said first metal.

5. Apparatus of the character described comprising an arm having an opening therein, a contact carried by said arm, said contact having a supporting portion of a first metal extending through said opening and said contact having a pair of heads, each having a diameter greater than the diameter of said opening and joined to said supporting portion, at least one of said heads formed in situ References Cited by the Examiner UNITED STATES PATENTS 2,241,262 5/1941 Keitel 200-166 2,796,495 6/1957 Keitel et al. 200-166 2,890,315 6/1959 Graves 200166 3,208,129 9/1965 Talbot et a]. 200-166 ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner. 

4. AS A NEW ARTICLE OF MANUFACTURE, A METAL BODY IN THE SHAPE OF A RIVET HAVING A HEAD FORMED AT LEAST IN PART BY A FIRST METAL, A STEM OF A SECOND METAL JOINED TO SAID HEAD WITH THE FREE END OF SAID STEM FORMED OF SAID FIRST METAL. 